In the months and years ahead, dynamic languages are going to take on an increasing important role in the .NET platform. To support this Microsoft is heavily investing in integration between the dynamic languages and the CLR.
Before we get into how that integration works, we have to take a moment to discuss open source. The most important dynamic languages on the .NET platform are IronPython and IronRuby. As both of these are under an open source license, they won’t follow the normal schedule for language changes. All open source languages officially supported by Microsoft will have two release cycles. There will be the release early/release often schedule common for open source projects, which of course results in a lot more rollouts. Parallel to this will be the formal, highly tested releases that Microsoft prefers. Companies and developers will have the option use either style of release, as both will use the same code base.
As for integration, is all revolves around the IDynamicObject interface. This acts as a method binder allowing each object to use the semantics of the language it was written in. The languages that will have binders out of the box include IronPython, IronRuby, JScript, and COM. Yes, COM is considered a dynamic language for this purpose of late binding and dynamic method invocation.
In addition to language specific binders, developers can have special rules for just a single class. The easiest way to do this is to start with the abstract class DynamicObject. What follows is a list of actions that can be overridden for custom behavior. As you browse the list you will undoubtedly see some actions not supported directly by the syntax in your language of choice.